1. Field of the Invention
The instant invention relates generally to the fields of biology and chemistry. More particularly, the present invention relates to novel insecticidal compounds, compositions thereof, and to methods of controlling (e.g., reduction or elimination) insects therewith.
2. State of the Art
Many ingredients are known for their insect repellant and killing properties. Most of these insecticides are toxic or harmful to human beings animals, and agricultural products, and are used in large amounts as insecticides. Because of environmental and regulatory considerations, the usage of insecticides are under increasing scrutiny with regards to such matters as toxicity, carcinogenicity, and air and ground water contamination. Some commercially-available insecticides have had their uses curtailed because of such considerations.
In an effort to address these considerations, in particular concerns regarding toxicity, a number of insecticides have been developed. One such insecticide is described in U.S. Pat. No. 2,347,265, issued to Hyman (xe2x80x9cthe Hyman Patentxe2x80x9d). The Hyman Patent describes preparation of insecticidal substances from raw materials containing alkyl substituted derivatives of naphthalene, which are found naturally occurring as minor components of mineral oils. These substances are isolated in small amounts from cracked fuel oils used commercially. As described and claimed in the Hyman Patent, the insecticidal compositions must be present in the oil phase of a prepared insecticide in order for the alkylated naphthalene contained therein to exhibit insecticidal activity. Additionally, the insecticidal compositions contain a mixture of substituted derivatives (i.e., a mixture of various isomers of substituted naphthalenes).
The insecticidal compositions of the Hyman Patent, however, are undesirable for use on plants or in agricultural settings, such as the storage of harvested crops (e.g., stored potatoes or grains). For example, use of oils on plants and stored agricultural products can accelerate production of molds, affect plant physiology (e.g., respiration), affect the taste of plants and agricultural products ultimately used as food products, stain stored agricultural products, and make the surface of the plant or agricultural product (including facilities storing the agricultural products or residential buildings having treated plants) sticky and susceptible to globing or coating with undesirable dust or contaminants. Also undesirable, from an environmental and regulatory standpoint, is that the Hyman Patent utilizes a xe2x80x9cmixturexe2x80x9d of substituted naphthalenes, some of which have characteristics relating to toxicity, effectiveness, and environmental contamination which are variable and, in some instances, unknown. With regard to variability, U.S. Pat. No. 3,080,278, issued to Douros et al., describes use of substituted naphthalenes as fungal growth inhibitors. As recognized therein, various isomers of dialkylnaphthalenes are inactive, whereas various mixtures of selected substituted naphthalenes, tested at the same concentration levels and under the same conditions, act as effective fungal growth inhibitors
To same effect, in U.S. Pat. No. 5,459,122, issued to Ford et al. (xe2x80x9cthe Ford Patentxe2x80x9d) there is described improved aromatic oil compositions containing naphthene-benzenes and dinaphthenebenzenes, and additionally containing substituted naphthalenes. These oils, in addition to having insecticidal characteristics, also have phytotoxic properties making them suitable for use as herbicides. This, however, makes these oils undesirable for use on plants or many agricultural products.
In view of the shortcomings of the aforementioned compositions and methods known in the art, it would be advantageous to provide insecticidal compounds, compositions thereof, and methods of controlling insects therewith that are free from oil adjuvants or oil carriers. It would be further advantageous to provide an insecticide that has low toxicity to humans or animals, that is composed of a single isomer of a known compound, that is effective for use as an insect repellant or insecticide, that can be used in agriculture both during growth and after harvest in storage and transit, and which can be used in buildings occupied by humans and animals.
A method, compound and composition for insecticidal uses has been discovered. Although various isomers and mixtures of isomers of the chemical dimethylnaphthalene have been used and suggested for various purposes, it now has been discovered that a particular isomer, 1,4-dimethylnaphthalene (xe2x80x9c1,4-DMNxe2x80x9d), is an effective insecticide. 1,4-DMN is effective when applied directly to insects, such as flies, moths, bees and the like, directly in liquid, or as a vapor or mist, and especially in confined spaces. 1,4-DMN is also effective when applied to or contained in various materials which is ingested by insects and when applied on plants, agricultural products, and food products. An insecticide formulation containing 1,4-DMN is effective in both low and high concentrations of 1,4-DMN in the formulation and when applied in low dosage and in high dosage rates. A significant advantage of 1,4-DMN is that it has low toxicity in humans and animals and may be used in contact with agricultural and food products. A further advantage of the insecticidal compounds and compositions of the present invention is that they are preparations which include substantially pure 1,4-DMN either alone or in combination with oil-free solvents.